Abstract

The ratites are a distinctive clade of flightless birds, typified by the emu and ostrich that have acquired a range of unique anatomical characteristics since diverging from basal Aves at least 100 million years ago. The emu possesses a vestigial wing with a single digit and greatly reduced forelimb musculature. However, the embryological basis of wing reduction and other anatomical changes associated with loss of flight are unclear. Here we report a previously unknown co-option of the cardiac transcription factor Nkx2.5 to the forelimb in the emu embryo, but not in ostrich, or chicken and zebra finch, which have fully developed wings. Nkx2.5 is expressed in emu limb bud mesenchyme and maturing wing muscle, and mis-expression of Nkx2.5 throughout the limb bud in chick results in wing reductions. We propose that Nkx2.5 functions to inhibit early limb bud expansion and later muscle growth during development of the vestigial emu wing.

Details

Title
Co-option of the cardiac transcription factor Nkx2.5 during development of the emu wing
Author
Farlie, Peter G 1   VIAFID ORCID Logo  ; Davidson, Nadia M 2 ; Baker, Naomi L 1 ; Raabus, Mai 2 ; Roeszler, Kelly N 2 ; Hirst, Claire 3 ; Major, Andrew 3   VIAFID ORCID Logo  ; Mariette, Mylene M 4 ; Lambert, David M 5   VIAFID ORCID Logo  ; Oshlack, Alicia 2   VIAFID ORCID Logo  ; Smith, Craig A 6 

1  Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC, Australia; Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia 
2  Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC, Australia 
3  Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC, Australia 
4  Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, Australia 
5  Environmental Futures Research Institute, Griffith University, Nathan, QLD, Australia 
6  Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC, Australia; Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC, Australia 
Pages
1-12
Publication year
2017
Publication date
Jul 2017
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1038/s41467-017-00112-7
ProQuest document ID
1923278617
Copyright
© 2017. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.